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At the present time, machines employed for the production of mechanical energy by internal combustion of organic fuel consist primarily of mechanical displacement machines, generally called xe2x80x9creciprocatingxe2x80x9d engines, and gas turbines.
Reciprocating internal combustion machines employ reciprocating mechanical motion of pistons and valves for working fluid manipulation and fuel combustion is a pulsed, non-continuous, process. The function of a reciprocating internal combustion engine is theoretically described in terms of a thermodynamic cycle such as first postulated by Sadi Carnot (1824) or one of the alternative thermodynamic cycles such as postulated by Nicholas Otto (1876), and Rudolph Diesel (1892). Gas turbines employ purely rotational components, aerofoil surfaces, and aerodynamic interaction for working fluid manipulation and fuel combustion is a self-sustaining continuous process. In general, gas turbines theoretically function in accordance with a thermodynamic cycle such as postulated by G. B. Breyton (1876).
Reciprocating machines offer an operationally flexible, relatively high torque power source and are economically satisfactory for many commercial applications, however their featured reciprocating components and pulsed combustion are inherent sources of undesirable noise and vibration. In comparison, gas turbine machines offer a relatively high rotational speed power source, and, relatively, reduced emissions of noise and vibration but offer economic superiority only in applications requiring relatively high measures of power density and delivered power.
Over a number of years significant inventive effort has been directed toward the derivation of a xe2x80x9crotaryxe2x80x9d internal combustion machine such as would feature mechanical displacement for working fluid manipulation but employ only rotationally dynamic components to accomplish fluid manipulation. By retention of the mechanical displacement means for working fluid manipulation the xe2x80x9crotaryxe2x80x9d machine is perceived to offer the performance characteristics given by reciprocating type machines, but, through elimination of reciprocating components, preclude their concomitant mechanical complexity and potential for emission of noise and vibration. The radial vane type rotary machine has been the subject of particular attention in this regard.
Conceptually the rotary vane machine primarily consists of a stationary containment structure and an internal assembly of rotationally dynamic components. The stationary containment structure consists of a containment cylinder with a precisely or approximately circular bore, installed with end closure structures. Ports are installed for induction of combustion air and for discharge of combustion products through the boundary of said containment structure.
The internal assembly of rotationally dynamic components primarily consists of a rotational armature, a plurality of radial vanes, and a means for extracting rotary power. Said rotational armature is precisely or approximately circular in cross section. The diameter of said rotational armature is less than the bore diameter of said containment cylinder such as to create an annular cavity between the peripheral surface of said rotational armature and the bore of said containment cylinder. Said rotational armature is fitted with a plurality of radial slots equally spaced around its periphery and parallel to its longitudinal axis. Each said slot accommodates and provides annular sliding support for one radial vane. Each said radial vane is a relatively thin structural panel axially extending through the armature length and radially extending from within said slot to contact or closely approach the bore of said containment cylinder. The plurality of said radial vanes subdivides the volume of aforesaid annular cavity into a plurality of annular segmental cells. Said rotational armature is supported such as to rotate on an axis parallel to, but radially displaced from the bore axis of said containment cylinder. Since the rotational axis of said rotational shaft is radially displaced from the bore axis of said containment cylinder, the relative volume of any given segmental cell is dependent upon its orbital location and, therefore, cyclically changes through rotation of said rotational armature. Said rotationally related cyclical change in relative volume functionally equates to the change in relative volume caused by the reciprocation of a piston within a cylinder such as employed in reciprocating type internal combustion and provides the basic features of working fluid manipulation necessary for the function of a heat engine cycle. For a given set of said containment cylinder proportions, the manipulated volume is inversely influenced by the diameter of said armature. Within certain limits, the compression ratio or expansion ratio of the volumetric cycle is directly influenced by both the number of segmental cells surrounding said rotational armature and the distance separating the rotational axis of said rotational armature from the bore axis of said containment cylinder. Said compression ratio is also influenced by the angular width and radial location of the sector allocated for the combustion air supply port. Similarly the expansion ratio is influenced by the angular width and radial location of the sector allocated for the combustion product discharge port. Means for extracting rotary power from the machine may consist of an axial extension of said rotational armature through one or both aforesaid end closure structures or by means of a rotational shaft functionally integrated with said rotational armature.
A number of patents have been awarded for rotary vane internal combustion machine concepts. However, despite the potentially excellent qualities offered by the rotary vane machine, as of this writing none of the concepts presented in prior art are known to have matured sufficiently to demonstrate practical utility. It may be reasonably hypothesized that the reason for such non-maturation is the result of singular or compounded inadequacies regarding functional viability considerations.
As known to persons skilled in the art, the fundamental functional viability of all machines is their capability to function within the constraints of common natural laws as defined in mechanics, physics, and mathematics. It is also known to persons skilled in the art that, beyond these fundamental considerations, the functional viability of an energy related machine is demonstrated by its capability to meet thresholds for efficiency, and power density within constraints of imposed by the physical properties of economically available constituent materials. The overall efficiency of thermal machines is the product of thermodynamic cycle efficiency and mechanical efficiency. The physical properties of constituent materials such as dimensional stability and lubricity may be significantly influenced by thermal environment. For these reasons the potential functional viability of a thermal machine may be theoretically assessed by analysis of its functional geometry and components features relative to thermodynamic cycle efficiency, mechanical efficiency, and thermal control considerations.
For internal combustion machines thermodynamic cycle efficiency is directly influenced by the compression ratio of the volumetric cycle. For machines based on Carnot principles, and with numerically equal compression and expansion ratios, the basic relationship between cycle efficiency (xe2x80x9cAir Standard Efficiencyxe2x80x9d) and compression ratio is described as:             η      c        =          1      -              1                  v                      (                          κ              -              1                        )                                                                                      Where:                        ⁢                          xe2x80x83                        ⁢                          η              c                                =                      xe2x80x83                    ⁢                      Cycle            ⁢                          xe2x80x83                        ⁢            Efficiency                                                        v          =                      xe2x80x83                    ⁢                      Compression            ⁢                          xe2x80x83                        ⁢            Ratio                                                        k          =                      xe2x80x83                    ⁢                      Universal            ⁢                          xe2x80x83                        ⁢            Gas            ⁢                          xe2x80x83                        ⁢            Constant                              
As previously noted, the compression ratio of a rotary vane machine is directly related to the plurality of the annular segmental cells surrounding the armature and inversely influenced by the relative angular extent of the induction port sector. Finite numerical analysis demonstrates that the threshold for adequate cycle efficiency is attained only when the plurality of radial vanes exceeds a certain minimum value and the angular extent of the induction port sector is less than a certain maximum value.
Mechanical efficiency is essentially the measure of mechanical energy conservation exhibited by a mechanism in the process of doing work. Mechanical efficiency is inversely influenced by the quantity of energy dissipated by frictional interaction between dynamically related components and, in this context, may be expressed as:             η      m        =                            P          i                -                  P          f                            P        i                                                                    Where:                        ⁢                          xe2x80x83                        ⁢                          η              m                                =                      xe2x80x83                    ⁢                      Mechanical            ⁢                          xe2x80x83                        ⁢            Efficiency                                                                    P            i                    =                      xe2x80x83                    ⁢                      Input            ⁢                          xe2x80x83                        ⁢            Power                                                                    P            f                    =                      xe2x80x83                    ⁢                      Power            ⁢                          xe2x80x83                        ⁢            Consumed            ⁢                          xe2x80x83                        ⁢            by            ⁢                          xe2x80x83                        ⁢            Friction                              
Power consumed by internal friction is the sum of the increments of power consumed by individual frictional components. In radial vane type rotary machines the radial vanes create the preponderance of the dynamically active mechanical interfaces and are, thereby, a particularly significant potential cause of power loss due to friction. Potential friction sources are; peripheral edge friction caused by sliding contact of said radial vanes with bore of said containment cylinder, axial end friction caused by sliding contact of axial ends of said radial vanes with non-rotating end closure components, and radial friction caused by sliding contact of the faces of said radial vanes with the supporting surfaces of said rotational armature. The magnitude of energy loss due to friction is also significantly influenced by the nature of the materials in sliding contact and the effectiveness of lubrication at the contact surface. Finite numerical modeling demonstrates that, in the plurality necessary to achieve thermodynamic cycle viability, the radial vanes alone could, potentially, incur friction losses of sufficient magnitude as to cause non-viability from a mechanical efficiency viewpoint. Minimization of the potential contributions of mechanical friction from all sources is therefore a vital consideration regarding the functional viability of rotary vane machines.
Machine component temperature is a source of concern from thermal expansion, component flexure, friction, and bearing life viewpoints. Dynamic components of internal combustion machines are exposed to heating from three sources, adiabatic heating due to gas compression, heat released by fuel combustion, and heat produced by the work done in overcoming friction. For this reason the functional viability of internal combustion machines is dependent upon adequate means for environmental control. Environmental control normally consists of the movement of liquid and/or gaseous heat extraction media across component surfaces. In general, the rate of heat extraction is directly influenced by the area of structural surface exposed to heat extraction media and flow rate of said heat extraction media across said structural surface. Extraction of waste heat from stationary components of reciprocating machines is accomplished by exposure of external surfaces to ambient air or liquid heat extraction media. Extraction of waste heat from the stationary enclosures of rotary vane machines may be readily accomplished by similar means. Environmental control for internal dynamic components is normally accomplished by circulation of air and liquid lubricant. In the case of reciprocating machines environmental control of dynamic internal components is facilitated by their functional assembly which precludes exposure of many components to high temperature working fluid and contains them within a stationary crankcase structure and thus readily accessible for internal circulation of environmental control media. In comparison the internal dynamic components of rotary vane machines are, relatively, more substantially exposed to contact with high temperature working fluid and their functional assembly makes them significantly less accessible for internal circulation of environmental control media. For these reasons the means for maintaining environmental control within the interior of the machine assembly is a vital consideration regarding the functional viability of rotary vane machines.
Several prior rotary vane machine disclosures present technical approaches toward minimization of friction particularly as related to sliding friction between radial vanes and containment cylinder bore but in general are substantially silent regarding the other functional viability issues discussed above. Principal features of several rotary vane type machines disclosed in prior patents are briefly reviewed below.
U.S. Pat. No. 2,590,132 issued to F. Scognamillo on Mar. 25, 1952 discloses a rotary cylinder rotary device. Said device features a stationary housing with an internal circular bore, end closure structures, and fluid transfer ports. Within said stationary housing a solid rotor is concentrically secured to a rotational shaft. Said rotational shaft is radially and axially constrained by two rotational bearings with one bearing installed in each said end closure structure. Said rotor is fitted with a plurality of axial slots uniformly distributed around its periphery. Each said rotor slot annularly constrains one radial vane such as to permit relative sliding motion. Each said radial vane is installed with a cylindrical extension at each end. Said cylindrical extensions engage a rotating ring at one end and a rotating disk at the other such as to radially constrain said radial vane. Said radial vane is constrained such that its outer peripheral edge remains a small distance from the said circular bore at all rotational positions. A spring loaded sliding seal is installed on the radial periphery of each said radial vane such as to maintain pressure contact with the circular said bore. Said rotating ring and said rotating disk are concentrically and mechanically connected by means of an annular cylinder. Said rotating ring, rotating disk, and annular cylinder assembly is and axially and radially constrained by a rotational bearing installed in one said end structure. Axial aligned sealing strips are installed on the outer periphery of said annular cylinder such as to maintain sliding contact with the circular said bore. Said annular cylinder is fitted with axial slots such as to permit radial passage of said radial vanes. Said radial vanes are axially constrained by contact with said rotating ring at one end and with said rotating disk at the other. Issues related to lubrication, and heat extraction are not discussed.
U.S. Pat. No. 5,568,796 issued to William R Palmer on Oct. 29, 1996 discloses a rotary compressor and engine machine system Said disclosure features a stationary housing with an internal non-circular bore, end closure structures and fluid transfer ports. Within the stationary housing a plurality of radial vanes is radially constrained by means of pivotal bearings installed on a rotating hub. Said radial vanes extend through a rotating circular annulus such as to closely approach the bore of said stationary housing. Said annulus are installed on rotational bearings such that said annulus rotates on an axis parallel to but separate from the rotational axis of the said hub. Said hub and said annulus synchronously rotate by means of gearing. The bore of said stationary housing is contoured such that the free ends of said radial vanes remain a constant distance from the bore of the said stationary housing. Seals are installed on the free edges of the said radial vanes to close the gap between the free edges of said radial vanes and the said stationary housing. The disclosure demonstrates that one said assembly can fulfill the expansion and discharge phases of a heat engine cycle, one said assembly can fulfill the induction and compression phases of the said heat engine cycle, and coupling of two said assemblies can fulfill all of the four required phases of a heat engine cycle. The disclosure is silent regarding means for sealing the axial ends of rotational components, centrifugal restraint of vane edge seals and issues related to lubrication, extraction of waste heat, and accommodation of functionally related geometric variations.
U.K. Pat. No. 468,390 issued to Drehkolben Kraftsmachinen G.m.b.H on Jul. 2, 1937 discloses improvements in and relating to rotary piston machines. Features presented in this disclosure consist of means by which uninterrupted combustion of fuel can take place at constant pressure, a means by which rotary machines can be made to function by combustion of different fuel types (e.g. pulverized coal), and a means by which throttle like devices may be installed on either the induction or the expansion side of a rotary machine for the purpose of performance control. The disclosure also presents methods by which two rotary vane devices may be non-mechanically coupled such as to collectively function such as to fulfill the four required phases of a heat engine cycle. The disclosure drawings illustrate a rotary device consisting of a stationary containment cylinder, a solid rotor installed on a rotational shaft, fitted with six radial slots and accommodating six radial vanes. The disclosure is silent regarding the mechanical features of the rotary vane device and issues related to extraction of waste heat and lubrication.
This disclosure presents a rotary vane internal combustion machine for efficient conversion of chemical energy, as contained in liquid or gaseous fuels, to rotational energy suitable for accomplishing mechanical work. Functional characteristics such as rotational velocity and power density are, in general, comparable to the functional characteristics of modern reciprocating internal combustion machines, however functional efficiency is enhanced by elimination of major reciprocating components, minimization of mechanical friction, and utilization of a continuously sustained combustion process. The machine primarily consists of a stationary containment structure and an internal assembly of rotationally dynamic components.
The stationary containment and foundation structure consists of a containment cylinder with circular bore installed with a closure structure at each axial end. Ports are installed for induction of combustion air and for discharge of combustion products through the wall of said containment cylinder. Said induction and discharge ports are mutually interspersed throughout the axial length of the aforesaid stationary containment cylinder, peripherally dispersed such as to minimize their collective sector width, and radially oriented such that their respective flow streams maximize working fluid manipulation efficiency. Ports are for introduction of fuel, externally supplied energy, and ports for maintaining combustion as a sustained continuous process are incorporated in the structural wall of said containment cylinder.
The internal assembly of rotationally dynamic components primarily consists of a rotational armature, a rotational shaft and a plurality of radial vanes. Said rotational armature features a circular cross section and a hollow core. The outside diameter of said rotational armature is approximately ninety percent of the bore diameter of aforesaid containment cylinder thus creating an annular cavity between the peripheral surface of the said armature and the said bore of aforesaid containment cylinder. Said rotational armature is simply supported by low friction rotational bearings installed in aforesaid end closure structures and rotates on an axis parallel to but radially separated from the bore axis of aforesaid containment cylinder. The annulus of said rotational armature accommodates a plurality of axially aligned radial slots uniformly distributed around its periphery. Each said radial slot is installed with one radially sliding radial vane and a pair of radially extending compression springs. Said radially extending compression springs are installed such as to exert a radially outward force on the associated said radial vane. An articulated extension is secured to the innermost edge of each said radial vane and to the periphery of said rotational shaft by means of hinged connections. Said rotational shaft is simply supported by, and extends through, a low-friction rotational bearing installed in each aforesaid end closure structure. Axial ends of said rotational shaft are configured to facilitate transmission of rotational power to external power consuming systems. The axis of rotation of said rotational shaft is coincident with the bore axis of said containment cylinder. The radial widths of said radial vanes and said articulated extension are selected such as to preclude contact between the outer edges of said radial vanes and the bore of said containment cylinder. By this means the centripetal force induced by each radial vane upon high-speed rotation of said armature is reacted by said rotational shaft and not through sliding contact with the bore of said containment cylinder. A mechanical radial vane edge seal installed on the outermost edge of each said radial vane exerts a nominal spring force on the bore of aforesaid containment cylinder. Said radial vanes and said radial vane edge seals subdivide the said annular cavity into a number of annular segmental cells. Axial ends of said annular segmental cells are closed by means of rotational assemblies consisting of a sealing ring, axial spring, and retainer ring components installed at each end of said rotational armature. Said sealing ring, axial spring, and retainer ring assemblies resiliently respond to axial component geometry adjustments such as caused by thermal variations. Since the rotational axis of said rotational armature is radially displaced from the bore axis of aforesaid containment cylinder, the relative volume of any given segmental cell is dependent upon its orbital location and, therefore, will cyclically change upon rotation of said armature. The described mechanism therefore fulfills the fundamental requirements for physical manipulation of working fluid necessary to achieve a functional heat engine thermodynamic cycle and, with selection of appropriate geometric relationships, support systems, and design details, be evolved to function as an internal combustion machine.
The internal axial cavity in aforesaid rotational armature provides a means for delivering environmental control media to internal dynamic components. Contouring the internal peripheral surface of the said internal axial cavity such as to enlarge the surface area exposed to environmental control media facilitates extraction of heat from said rotational armature and interfacing components. Environmental control media are supplied to and discharged from said internal axial cavity by means of ports installed in the aforesaid end closure structures.
Necessary ancillaries consist of an air supply fan, fuel delivery system, an externally powered rotational device to initiate machine rotation, an electrically powered igniter to initiate combustion, and a liquid lubricant management system.
The internal combustion rotary machine presented in this disclosure illustrates the primary geometric relationships and other design features appropriate to obtaining the measures of thermodynamic efficiency, mechanical efficiency, and internal environmental control necessary for demonstration of functional viability.